1. FIELD OF INVENTION
Antiosteoporosis method applicable to a patient or subject having an intact weight-bearing bone structure and means for carrying out the same; inducing strengthening and growth of preosteoporotic and osteoporotic bone, especially in the lower extremities and in the hips, by the application of intermittent, dynamic loading according to a novel method and employing novel mechanical means.
2. PRIOR ART
Osteoporosis is characterized by a gradual, initially painless decrease in bone tissue, leading to increased susceptibility to fractures. It affects at least fifteen million Americans and occurs when the rate of breakdown of bone tissue exceeds the rate of new bone formation, a condition often referred to as "negative calcium balance", although many risk factors besides mere calcium deficiency are involved. The bones become weaker and more porous, even though the chemical composition of the bone tissue remains unchanged. The risk of osteoporosis increases with age. The degree of bone loss is a pathological exaggeration of the normal but gradual bone loss after the age of 35, and it is much more prevalent in Caucasian women than in men. It has become a problem of major medical significance for which there is no simple immediate solution. It is a problem crying for any type of alleviation or amelioration.
The United States Patent Office Subclass 128/419F is concerned solely with "bone growth stimulators" and approximately fifty-four patents have been located in this subclass, going back to 1975, all of which patents have been found to be related to some sort of electrical stimulation for the purpose of bone growth stimulation for the purpose of fracture healing.
After concluding the search in 128/419F and studying the patents classified in that particular subclass, a further search for mechanical types of bone growth or antiosteoporosis methods and devices, as opposed to electrical stimulators, was initiated in Class 128, Subclasses 33 and 70, directed to "vibrators, couch, chair or other support" and "osteal adjustors". The most relevant patents turned up by this additional search, and an interview with the Examiner in Group 330 in charge thereof, were U.S. Pat. Nos. 2,243,013 2,696,207, 2,902,993, 3,060,925, 3,081,085, 3,752,153, 3,835,844, and 4,432,353. Of these additional patents turned up by this additional research U.S. Pat. No. 2,902,993 related to a vibrating platform useful as a massage device as did U.S. Pat. No. 2,243,013, whereas U.S. Pat. No. 2,696,207 related to a rocking hospital bed, U.S. Pat. No. 3,060,925 related to a particular type of oscillating treatment table, U.S. Pat. No. 3,752,153 related to a headstand exerciser, U.S. Pat. No. 3,835,844 related to an apparatus for stretching the spine, and U.S. Pat. No. 4,432,353 related to a kinetic oscillating treatment platform constituting a therapeutic bed for immobilized patients.
Further private studies and investigations were conducted. An article by Lanyon and Rubin entitled "Regulation of Bone Mass in Response to Physical Activity", appearing in "Osteoporosis, A Multi-Disciplinary Problem", 1983, by the Royal Society of Medicine International Congress and Symposium Series No. 55, reiterates the known fact that there is a casual relationship between functional activity and bone architecture although the mechanism by which it operates, and its specific structural objectives, remain undefined. This publication also indicates that bones put under stress result in an "osteogenic response" and that a functional level of bone mass, having been once achieved, will be maintained only if the exercise regimen involving "mechanically-related osteogenic stimulus continues". The authors likewise suggest strains at relatively fast rates as compared to low rates and an intermittent load regime with remarkably few load applications. Likewise, a "bone-shaker" frame which reportedly can reduce healing time for bone fractures has been disclosed in Medical World News for Apr. 28, 1986, and the article entitled "Mechanical Loading Histories and Cortical Bone Remodeling" by Carter in Calcified Tissue International (1984) 36:S19-S24, makes further suggestions as to the magnitudes, orientations, and sense (tension or compression) of the physiologically-incurred cyclic principle strains of cortical bone throughout the skeleton. Further, the article entitled "Review of Wolff's Law and Its Proposed Means of Operation" by Treharne in Orthopaedic Review, X, No. 1 for January of 1981, pp 35-47, illustrates once again that "Every change in the function of a bone is followed by certain definite changes in internal architecture and external conformation in accordance with mathematical laws", which is a simple restatement of Wolff's Law going back to his treatise issued in 1892 entitled "The Law of Bone Transformation", and includes citations to publications indicating the highly complex nature of the problem, e.g., that the application of force to in vitro cartilage cells causes a decrease in cyclic AMP content, indicating that collagen synthesis and cellular mytosis may have increased and giving rise to the hypothesis that, if cells can respond directly to a physical load, then it is even possible that hormonal and mechanical factors may regulate cells by common pathways. In the "Concluding Remarks" the author states that Wolff's Law, or the remodeling of bone in response to changes in load, is a "commonly observed medical phenomenon", although "The exact means by which bone modulates its mass and responds to changes in physical load has yet to be clearly understood and proven."
Then, in the Journal of Bone and Joint Surgery, Incorporated, Volume 66A, No. 3, for March 1984, Rubin et al. in an article entitled "Regulation of Bone Formation by Applied Dynamic Loads" conclude that "functional load-bearing prevents a remodeling process that would otherwise lead to disuse osteoporosis" and that "Functional levels of bone mass in patients may only be maintained under the effects of continued load-bearing" as well as that completely reasonable load regimens prevent an intracortical resorption and are associated with substantial periosteal and endosteal new-bone formation. Also that "The osteogenic effect of an unusual strain distribution suggests that a diverse exercise regimen may engender a greater hypertropic response than an exercise program that is restricted", and that "A substantial osteogenic response may be achieved after remarkably few cycles of loading". The conclusions of these authors were based on their studies which required the placement of metal pins in the ulnas of skeletally-mature roosters after the bone had been osteotomized, after which force was transmitted to the bone by means of these pins.
Along the same lines is the Woo, et al. article entitled, "The Effect of Prolonged Physical Training on the Properties of Long Bones: A Study of Wolff's Law" in the Journal of Bone and Joint Surgery, Vol. 63A, June 1981, pp. 780-787. In their experiments on immature swine femurs, the authors found that animals subjected to an exercise program developed increased cortical thickness of the bone. Other animal studies using various other exercise protocols have found similar results.
More or less to the same effect are additional relatively-recent publications indicating that intense physical activity, such as hours of long distance running or the like, produces a significant elevation in the bone densities of the participants. Representative of these publications are the following:
Smith, "Exercise and Osteoporosis", British Medical Journal, Vol. 290 for Apr. 20, 1985, at pages 1163-1164; Article in Support of Smith by Hollo and Gergely in British Medical Journal, Vol. 290 for June 22, 1985 at page 1902. l
Lane et al., article entitled "Long-Distance Running, Bone Density, and Osteoarthritis", in the JAMA for Mar. 7, 1986, Vol. 255, No. 9, pages 1147-1151.
Aloia et al., article entitled "Prevention of Involutional Bone Loss by Exercise", in the Annals of Internal Medicine 89:356-358 (1978).
Krolner et al., article entitled "Physical Exercise as Prophylaxis Against Involutional Vertebral Bone Loss: A Controlled Trial", in Clinical Science 64, 541-546 (1983).
The paper entitled "Osteoporosis and Exercise" by Smith et al. presented at Second Acta Medica Scandinavia International Symposium: Physical Activity in Health and Disease on June 10-12, 1985.
Yeater et al., article entitled "Senile Osteoporosis--The Effects of Exercise", in Postgraduate Medicine 75, No. 2, for Feb. 1, 1984, pp. 147-163.
Smith, "Exercise for Prevention of Osteoporosis: A Review" in The Physician and Sports Medicine 10, No. 3, for March 1982, pp. 72-83.
Smith et al., article entitled "Physical Activity and Calcium Modalities for Bone Mineral Increase in Aged Women" in Medicine and Science in Sports and Exercise 13, No. 1, pp. 60-64 (1981), and
Korcok, article entitled "Add Exercise to Calcium in Osteoporosis Prevention", JAMA 247, No. 8, 1106-1112 (1982).
Numerous others may be mentioned, but the foregoing are submitted as representative.
All of the foregoing suggest that osteoporosis might possibly be ameliorated or avoided, and that new bone growth may be stimulated, by the application of load-bearing or load-producing strains upon the bones of interest (such as are afforded by vigorous or even intense exercise), but none of the foregoing or any other publication known to me, whether patent or medical or otherwise, has suggested how this may be accomplished either conveniently or economically in a patient or subject and not a mere laboratory animal, much less mechanically or with any long-term or permanent effect. Moreover, the aforementioned exercise regimens required routines not likely to be accepted by large segments of the population, much less over extended periods of aging. To be acceptable and efficacious, the program must be performable on a continuing basis for year after year. For example, the study by Smith, et al. required an individual to exercise at a strenuous level for at least 45 minutes per day.
A very recent publication in The Journal of Bone and Joint Surgery, Incorporated, Vol. 68A, No. 7, pp. 1090-1093 (September 1986), by Margulies et al. entitled "Effect of Intense Physical Activity on the Bone-Mineral Content in the Lower Limbs of Young Adults", shows that fourteen (14) weeks of strenuous physical training increased the average bone-mineral content of the left leg in those completing the course by 11.1% and of the right leg 5.2%, indicating that in young adults a high level of bone loading can result in a rapid increase in bone-mineral content in those people able to engage in strenuous physical exercise. Of course, this does nothing for the large part of the population which is prone to osteoporosis or suffering from osteoporosis and which is not able to engage in intense physical activity, and oftentimes able to engage in little or no physical activity at all (Cf. FIGS. 16 and 17 hereof).
An important feature of the present inventive method and apparatus, therefore, is that the number of repetitions and the peak forces achieved are controllable and can thus be limited in duration and force applied. Over-zealous activities or highly-repetitive military drills or athletics may lead to actual fractures or the so-called "stress fractures" as frequently occur today with, for example, marathon runners or with new military recruits. Mere exercise places uncontrolled forces across the joints and on the bones.
It has accordingly remained an open question for the medical profession as to just how these theories and observations might be put into some practical and economic method and means whereby bone-growth stimulation, particularly in the prevention or treatment of osteoporosis in a patient or subject having an intact weight-bearing bone structure, and especially in the lower extremities and in the hips, could be effected reasonably and conveniently and by employing a practical and economic method and utilizing relatively simple means. It is a major objective of the present invention to provide such a long-awaited solution to the problem.
Paraplegics, quadriplegics, and others suffering from any of numerous neurologic and/or musculoskeletal disorders also frequently develop severe osteoporosis because they cannot place normal stress on the bones of the spine and lower extremities as occurs normally with ambulation and normal activities of daily living associated with normal gait and weight bearing. These individuals may not be capable of participating in a weight-bearing exercise program necessary or desirable to prevent bone loss and osteoporosis. They do, however, frequently incur fractures, often with devastating consequences as a result of their osteoporosis. The method and apparatus of the invention may offer the only reasonable approach to prevention or treatment of osteoporosis in such impaired individuals.
A further significant group comprises the residents of nursing homes who are frequently restricted to beds or wheelchairs due to general debility. Among this group, the fractures which result from osteoporosis are potentially catastrophic, with fifteen percent of these individuals who sustain an osteoporosis-related hip fracture dying within one year of the fracture, making hip fracture the twelfth leading cause of death.
The problem of osteoporosis is also a major concern of astronauts. On space flights longer than ten days, severe loss of calcium results due to the weightlessness of space and the fact that stress is not applied to the bones. This has been summarized by Whedon, G. D., et al. in their report, "Mineral & Nitrogen Metabolic Studies, Experiment M071", in Biomedical Results from Skylab, U.S. Government Printing Office, Deitlein, L., Editor, Washington, D.C., pp. 164-174 (1977). Extensive research to date has not resulted in an acceptable solution to the problem of osteoporosis resulting from weightlessness. The ineffectiveness of these measures was reviewed by Schneider, V. S., and McDonald, J., in their article, "Skeletal Calcium Homeostasis & Countermeasures to Prevent Disuse Osteoporosis" in Calcified Tissue International, 36:S151-S154 (1984). The method and apparatus of the invention is equally applicable in space where raising of the platform presents no problem, but where the dropping step must be effected using a force other than gravity, e.g., spring loading or centrifugal force, since the usual gravitational force for this purpose is not present in space.
When a patient or subject having an intact weight-bearing bone structure is referred to herein, such a patient or subject has a leg, hip, and spinal structure without stress or other fractures therein, and otherwise uninjured in said leg, hip, and spinal structure, since the present invention is clearly not designed or intended for bone fracture healing and its application to a patient or subject having bone breaks or fractures, whether from stress or of a more serious nature, would not only be detrimental to the patient but also extremely dangerous for reasons which will be apparent to one skilled in the art and which will become further apparent hereinafter.